Pump



Nov. l, 1947, A. zlsKA PUMP Filed Nov. 8, 1943 3 sheets-sheet l 0V. u,ww.

A, ZISKA PUMP 3 sheets-sheet 2 Filed Nov. 8, 1943 hm. 9m.

IN VEN TOR.

Nw. u, M7. A. zlsKAi 430,753

PUMP I Filed NOV. 8, 1945 5`SheetS-Sh6el2 5 s N W l/ Q v Q2 mfc/z.

A12/w Z/fm Pat'ented Nov.Y l l, V1947 Adam Ziska, Wauwatosa, Wis.Application November 8I 1943, Serial No. 509,343

This invention relates to pumps. Objects of this invention are toprovide a pump 1'3 Claims. (Cl. 103-162) in which the cylinders arearranged in a revolvv ing rotor and the pistons reciprocate back andforth in the cylinders parallel to the axis of rotation of the rotor,and to so arrange the parts that mechanically the entire rotatingassembly is accurately balanced about the center of rotation.

Further objects are to provide a pump having the cylinders formed in arevolving rotor and the pistons located within the cylinders, which isso arranged that the hydraulic pressures on.v diametrically opposedsides at each end of the rotor are balanced so that there is no pressuredue to the hydraulic pressure transmitted to the main bearings of theshaft of the rotor, and to so arrange the cylinders that the reactiondue to hydraulic pressure axially of the shaft is balanced so that therewill, therefore, be no end thrust at either end of the shaft due tohydraulic pressure, thus minimizing friction and wear at the bearingsand on the revolving rotor.

Further objects are to provide a pump adapted .to pump iluid andprimarily designed to pump a liquid such as oil, which'is so made thatthe pump may be made in a very small physical size and yet will have arelatively large capacity, and to so design the pump that it can be usedto produce any desired pressure'up to a very high Pressure if sodesired.

Further objects are to provide a pump having rotating cylinders withpistons therein, in which a piston controlling member in the form of aball bearing is carriedby a pivotally mounted yoke and is arranged toengage the pistons between the active ends thereof and to cause thepistons to oscillate back and forth to any desired extent to therebycontrol the volume of liquid displaced by the pump, and to so arrangethe apparatus that the pump is` reversible by merely rocking the yokeabout its pivotal axis, the yoke when in neutral position causingcessation of pumping.

Further objects are to provide a pump. having rotating cylinders withpistons therein which is so arranged that no charging mechanism isrequired but instead in which the pistons while executing pumping actionat one end are executing a positive suction action at the other end.

In greater detail, objects of this invention are to provide a pumphaving a series of rotating cyl-l inders with pistons therein which isso made that series of pistons, a section being located at each end ofthe rotor with the pistons actuated interthere are two sectionsof therotor with the two mediate their ends, and to so construct the parts ofthe pump that they may be produced by simple turning and yboringoperations without requiring elaborate curing.

Further objects are to provide a pump of the above defined characterwhich'is very simple to make and which, as has been indicated, may beproduced by simple machine shop methods without requiring any specialapparatus whatsoever.

Embodiments of the invention are shown in the accompanying drawings, inwhich:

Figure 1 is avertical sectional view through the pump, such viewcorresponding to a section on the line l-l of Figure 2 with the parts,however, arranged in their neutral position.

Figure 2 is'a horizontal sectional view on the line 2-2 of Figure 1 withthe parts, however, arranged in one of their pumping positions.

Figure 3 is a view oi" the left-hand ring, such view being partly insection.

Figure 4'is a sectional lview on the line 4 4 of Figure 3.

Figure 5 is a top plan view of the pump, such view being drawn to asmaller scale and showing-y the means for controlling the pump. Figure6is a sectional view on the line 6-6 of Figures 1 and 2, the direction offlow of the liquid being in accordance with the position of the partsshown in Figure 2. f i

Figure 7 is a sectional'view on the linezl-- of Figures 1 and 2, thedli'ectionof ilow ofthe liquid being in accordance with the positionofthe parts shown in Figure 2. f

Figure 8 is a sectional view on the line 8 8 of Figures 2, 6 and 7, thedirection of flowof the liquid being in accordance with the setting ofthe parts shown in Figure 2.

Figure 9 is a fragmentary top plan view of a modified form of controlmeans for the pump.

Figure 10 is a view drawn to a reduced scale showing the semicircularkeys for locking the left-hand end of the shaftagainst displacement tothe left as viewed in Figure l.

Referring to the drawings, it will be seen that the pump comprises abody portion vl which may be provided with oppositely projectingapertured feet 2 whereby it may be secured to any suitable support. Thebody portion is bored straight through from lend to end to provide thecylindrical bore 3. Within this bore a right-hand ring 4 and a left-handring 5 are located and have a, pressed fit and form a unitary portion ofthe body portion of the device. These right and left-hand rings areprovided respectively with arcuate channels 6, l, 8 and 9 respectively.The channels 3, 1, E8 and 9 extend approximately half way around each ofthe rings, as shown most clearly in the sectional views of Figures 6 and7. Ports are formed in the body portion 'communicating with the channelsby drilling straight across the body portion, as shown in Figures 7 and8. \The holes are subsequently plugged by the threaded plugs shown inFigures 6 and '1. The ports are indicated by the reference charactersIll, Il, I2 and I3. 'I'he ports II) and I2 communicate by means ofpassageways I4 and I5 with a transverse passageway I6 which in turncommunicates with a pipe I1. These ports may be drilled and the openingsnot used may be closed by means of screw threaded plugs as shown. Theports I I and I3 communicate by means of passageways i8 and v I9 with atransverse passageway 20 which in turn communicates with the pipe 2|,see Figure 2. These passageways may be drilled if desired and the endsnot used may be closed by means of screw threaded plugs as indicated.

The rings 4 and 5 are provided with inner channels on opposite sidesthereof. These inner channels are indicated respectively by thereference characters 22, 23.and 24, 25. The inner channels 22. 23 and24, 25 communicate respectively, by means of a plurality of openings asshown, with the outer channels 6, 1, 8 and 8. The rings 4 and are alsorespectively provided with pairs of channels 26, 21 and 23, 28. Theseinner pairs of channels are pressure or thrust balance channels as willappear hereinafter. It is to be distinctly understood, however, that inplace oi.' having the channels arranged in pairs, a single channel mayreplace each of the pairs of channels 2B, 23, 21, 21, 28, 28 or 29, 29,provided such channel is twice as wide as and coextensive with a singleone of the channels. It is preferable, however, to have these channelsarranged in- -pairs and located symmetrically on opposite sides oi themain channels 22, 23 and 24, 25. It is to be noted that the channels 26,21 and 28, 29 appear in Figures 6 and '7 in dotted lines and are`almostcomplete semicircles.

In the ring 4 the pressure balancing channels 26 are located on oppositesides of the channel 22 and the pressure balancing channels 21 arelocated on opposite sides of the channel 23. In the ring 5 the pressurebalancing channels 28 are located on opposite sides of the channel 24and the pressure balancing channels 29 are located on opposite sides ofthe channel 25. The channels 26 communicate with the channel 1 andthechannels 21 communicate with the channel 6 in the ring 4. In the ring 5the channels 28 communicate with the channel 9 and the channels 29communicate with the channel 8.

The manner in which this communication is obtained is shown for theleft-hand ring in Figures 3 and 4. It will be seen in reference toFigure 3, for instance, that the channel 9 communicates with thechannels 28 by means of the slanting passageways 30 and that the channel8 communicates with the channels 29 by means of the slanting passageways3l. The right-hand ring has the same channels, not shown, which, asstated, place the channel 1 in communication with the channels 26 andthe channel 3 in communication with the channels 21. 1

The sum of the widths of the channels 26 equal to the width of thechannel 23 and the sum of the widths of the channels 21 is equal to thewidth of the channel 22 for the ring 4, and similarly for the ring 5 thesum of the widths of the channels 28 is equal to the width of thechannel 25 and the sum of the widths of the channels 23 is equal to thewidth of the channel 24 and they are all co-extensive in length.

The purpose for the above described construction is apparent when it isconsidered that the pressure in the balancing channels 26 is the same asthe pressure in the channel 23 and the pressure in the balancingchannels 21 is the same as the pressure in the channel 22 for theright-hand ring 4, and for the left-hand ring the pressure in thebalancing channels 29 is the same as the pressure in the channel 24 andthe pressure in the balancing channels 28 is the same as the pressure inthe channel 25. From thisit will be seen that the thrust applied atdiametrically opposite portions on the two main sections of the rotorhereinafter described is identically the same and consequently notransverse thrust or pressure due to the liquid pressure is transmittedto the ball bearingsnsupporting the rotor and the ball bearingssupporting the rotor are, therefore, called upon only to sustain theweight of the rotor and are not called upon to sustain any unbalancedpressure due to the hydraulic pressure generated by the pump. Thus itwill be seen further that the channels26, 21 and 28, 23 are in realitythrust balancing channels.

The rotorcomprises a right and a lett-hand portion 32 and 33respectively. These rotor sections are rigidly keyed as shown to theshaft 34 which may be driven in any suitable manner. The right-handsection 32 of the rotor is provided with a plurality of cylinders 35,and the left-hand section 33 of the rotor is provided with a pluralityof cylinders 35. A slanting passageway or port 31 extends outwardly fromeach of the cylinders 35 and opens outwardly throughA the externalperiphery of the right-hand section 32 of the rotor. Similarly thecylinders 36 are each provided with slanting passageways 38 which openoutwardly through the outer periphery oi the left-hand section 33 of therotor. The outer ends of the cylinders 35 are closed by means ofthreaded plugs 39 and the outer ends of the cylinders 38 are closed bymeans of the threaded plugs 40.

A plurality of double-ended pistons are provided and are indicatedgenerally by the reference character 4I, These pistons are provided withpiston portions 42 at their right-hand ends and piston portions 43 attheir left-hand ends which respectively iit within the cylinders 35 and38. The intermediate portions of the pistons 4I are reduced and eachpiston carries a pair of flange members 44 located on opposite sides ofthe reduced portion.

A piston controllingor reciprocating member in the form of a ballbearing indicated generally by the reference character 45 is positionedcentrally of the pump.' This piston controlling member consists of anouter race 46 which has a pressed t with a yoke 41. It is heid in placeby means of the ring 48 which may, if desired, be a split ring. Theinner race of the piston controlling member 45 is indicated by thereference character 49 and between the two races a plurality of balls 55are positioned. The inner race 49 clears the central reduced portion ofthe piston 4I and the inner race is provided on opposite sides withinwardly slanting faces 5I which engage the curved faces of the flanges44 of the pistons. During operation of the pump the inner race 49travels around with the pistons.

It is to be noted that the yoke 41 is provided with a lower trunnion 52which is mounted withthe body portion I, as shown in Figure 1.

in a. bushing 53 in the body portion I and the hole in which the sleeve53 is` mounted isclosed by means of a bottom plate 54. The yoke isprovided with a bottom collar portion 55 which rests on a shoulderformed on the body portion I, as shown in 'Figure 1. The upper end ofthe yokeis provided with an upper trunnion 56 which is carried within abushing 51'which in turn is carried by a cap 58 secured to the upperside of The upper portion of the yoke is provided with an upper collarportion 59 which bears against a suitable shoulder formed on the cap 58.The bushings 53 and 5'I are pressed into place in accordance with theusual practice. 'The trunnion 58 extends outwardly beyond the collar 58and may be provided, as shown in Figure 5. with an operating handle ormember 60 rigidly secured thereto as shown and provided with an arcuateslot 6I through which a locking bolt 62 passes. This hand lever isadapted to be shifted to either side of center to thus rock the yokeinto the extreme position shown in Figure 2 on one side of `center or torock the yoke into the extreme position on the other side of center orto any intermediate positions, or to hold the yoke in a neutral positionas shown in Figure 1.

Any other suitable means may be provided for A rocking vthe yoke. Forinstance, the operating member 62' shown in Figure 9 may be actuated bymeans of a link 63 connected toany automatic control means or to amanual control means as desired. 'I'he member 62' is provided with anarcuate slot Stand the cap 58 carries a limit pin 65 to limit theextreme rocking motion of the member 52 on opposite sides of center.

'I'he shaft 34 is carriedvat opposite ends by ball bearings indicatedgenerally at 66 and 61. The ball bearing 86 is carried in the right-handend plate 68 and the ball bearing 61' is carried in the left-hand endplate 69. The shaft is prevented from moving to the right asviewed inFigure 1 by means of the integral collar I0 which is adapted to coactwith the inner race of the ball bearing 66 to prevent right-handshifting of the shaft. The left-hand end of the shaft is provided withagroove II within which an annular split key 'I2 is seated. This splitkey is surrounded by. means of a ring 'I3Y which is pressed on to thekey and holds the two halves of the key 'I2 in place as shown mostclearly in Figure 10. The annular key 'I2 is adapted to coact'with theinner race of the ball bearing 81 to prevent left-hand shifting of theshaft 3'4.

It is to be understood that the coacting parts of the pump areaccurately ground and are ac- -curately fitted. The pump is adapted topump psageways 38 into the channel 24 and from this channel it isdischarged into the channel 8. The channel 8 communicates 'with thechannel I9 and the channel 28 and nally with the discharge pipe 2i. Onthe lower half of the leithand end of the pump the pistons 4I aretraveling to the right as viewed in Figure 2 and are sucking liquid fromthe inlet pipe I'I through the channels I6 and I5 and the arcuatechannels 8 and 25. On the right-hand end of the pump on the lower halfthereoi'r'the pistons 4I are traveling to the right as viewed in Figure2 and consequently are pumping liquid from the cylinders 35 through theapertures 31' into the channel 23 and from there into the channel 1. Theliquid is discharged through the channels I8 and 20 to the dischargepipe 2|. On the upper half of the right-hand portion of the pump thepistons are traveling to the left as viewed in Figure 2 and consequentlyare drawing liquid into the cylinders 35 through the inlet pipe I 1 andthrough the channels IS and I4 through the annular channels 6 and 22.

-' under pressure in the channel 24 is transmitted The pressuredownwardly on the left-hand portion of the rotor, see Figure 6, due tothe fluid liquid in'the channels 26 and consequently no thrust isimparted. to the shaft due to the hydraulic pressure as the channels 26are coextensive in total width and length with the channel 23. If thelpiston controlling member'is moved position shown in Figure 2. It willbe seen that y during the rotation of the rotor, the upper half of therotor is pumping on the-left-hand end of the pump and the lower half ofthe ro-tor is pumping on the right-hand end of the pump. The pistons 4Iare traveling to the left as viewed in Figure 2 for the upper halfportion of the rotor and consequently are pumping liquid out of thccylinders 36 of the rotor section 33. The liquid is discharged from thecylinders 36 through the to the other side of center from that shown inFigure 2, the pressure of the liquid in the chan"- nels 25 and 28for-the left-hand portion of the rotor and the pressure in the channels22 and 2'I for the right-hand end of the rotor will exactly balance inexactly the same manner and for the same reasons as that previouslydescribed, and consequently no thrust will be imparted to the shaft.

The balancing is complete for each section of; the rotor and there is nolateral thrust tending to rock the shaft laterally about a pointintermediate its ends. In addition to this the shaft has no longitudinalthrust imparted thereto due to the pressure of the liquid. The right andlefthand rotor sections 32 and 33 bear respectively against the collarI8 and the annular key 'I2 and the thrusts in opposite directionsimparted to the members 32 and'33 of the rotor are exactly equal andconsequently are balanced and there is, therefore, no tendency to drivethe shaft in either direction'axially of the shaft. The supporting ballbearings indicated generally at 86 and 61 are therefore not called uponto carry any thrust in any direction due to the pressure of the liquid.I

In addition to this it is to be noted particularly that the right-handring 4' does not withstand any thrust. from the rotor 32 due to fluidpressure and similarly the left-hand ring 5 does not withstand anythrust from'the rotor due to fluid pressure as is apparent from theabove description.

The result of this accurate balancing of hydraulic pressure is thatthere is the minimum 7 wear between the right and left-hand sections ofthe rotors 32 and 83 and the right and left-hand rings 6 and 5respectively, and there is also the minimum wear on the bearingssupporting the axes when the piston controllingv member 45 is moved toeither side of the neutral position shown in Figure l as the flangemembers 44 ride either further out or further in on the inner race 49 ofthe piston controlling member 45. This imparts, as stated, aslightVoscillatory or rotary motion to the pistons back and forth about theirlongitudinal axes and consequently insures uniform wear between thepistons and the walls of their cylinders.

Another important feature of the pump forming the subject matter of thisinvention is that there is no tendency due to hydraulic pressure to rockthe yoke about its vertical axis out of position. It is to be noted thatthe yoke 41 is pivoted about a vertical axis and when it is rocked toone shift the piston controlling member to either side of neutral with'a minimum eiort. There is a tendency to rock the yoke about a horizontalaxis but in View of the fact that the trunnions 56 and 52 are widelyspaced and are relatively large, it is apparent that this tendency isreadily resisted.

It is to be noted also that there are no unbalanced masses which wouldtend to cause vibration about the longitudinal axis of the shaft evenwhen the pump is run at a high speed.

Another point of considerable importance in the actual manufacture ofthe pump is that practically all of the main surfaces are easilymachined. For instance the main body portion of the pump is boredstraight through from end to end and the rings 4 and 5 are readilyturned on a lathe and are bored out from end to end. Also it is to benoted that the cylinders are formed by drilling straight through eachsection of the rotor.

It is to be noted also that though the pump is rotated in one direction,nevertheless the flow of fluid through the pump may be reversed or maybe stopped entirely by respectively shifting the yoke to one or the Vother side of neutral or moving the yoke back to neutral. It is to benoted also that the yoke may be shifted from neutral to maximum oneither side of center to thus cause the pump to pump the liquid at anydesired rate from zero up to its maximum capacity.

It will be seen that the pump forming the subject matter oi thisinvention can be used to produce any desired pressure even up to a veryhigh pressure.

It will be seen that the pump forming the sub- -lect matter of thisinventionl is so organized that the forces are balanced and consequentlyminimum lWear results. It Awill also be seen that the pump may be veryreadily produced by simple machine shop operations.

It is to be noted that the pistons are positively driven in bothdirections and consequently the 8 pistons execute a positive suctionaction at one end whilei they compress the liquid at the other end andthus there is no necessity for a charging mechanism to charge thecylinders with oil.

It is to be understood that although a ball bearing has been shown, anysuitable type of antifriction bearing could be employed for the pistoncontrolling member. Obviously, other changes could be made where they donot affect the spirit of the invention and, therefore, although thisinvention has been described in considerable detail, it is to beunderstood that such description is intended as illustrative rather thanlimiting, as the invention may be variously embodied and is to beinterpreted as claimed.

I claim:

1. A pump comprising a, cylindrical rotor having a plurality ofcylinders therein, pistons mounted within the cylinders, means forreciprocating. the pistons as the rotor rotates, a body portionsurrounding the rotor and having arcuate suction and delivery channelsron opposite sides of the rotor arranged for successive communicationwith the cylinders as the rotor rotates and having open sides closed bythe cylindrical surface of the rotor, said body portion having at leastone thrust balancing channel diametrically opposite the delivery channeland directly communicating with the delivery channel and having an openside closed by the cylindrical surface of the rotor, whereby thepressure produced in the delivery channel is transmitted directly to thethrust balancing, channel diametrically opposite the delivery channel.

2. A pump comprising a cylindrical rotor having a plurality of cylinderstherein, pistons mounted within the cylinders, said pistons and saidcylinders having their axes paralleling the axis of rotation of therotor, means for reciprocating the pistons as the rotor rotates, a bodyportion surrounding the rotor and having arcuate suction and deliverychannels on opposite sides of the rotor arranged for successivecommunication with the cylinders as the rotor rotates and having opensides closed by the cylindrical surface of the rotor, said body portionhaving at least one thrustbalancing channel diametrically opposite thedelivery channel and directly communicating with the delivery channeland having an open side closed by the cylindrical sur. face of therotor, whereby the. pressure produced in the delivery channel istransmitted directly to the thrust balancing channel diametricallyopposite the delivery channel.

3. A pump comprising a cylindrical rotor having a 'plurality ofcylinders therein, pistons mounted within said cylinders, means forreciprocating said pistons as said rotor rotates, a body portionsurrounding said rotor and having arcuate delivery and suction channelson opposite sides of said rotor arranged to successively communicatewith said cylinders as the rotor rotates and having open sides closed byciprocating said pistons as saidrotor rotates,

a body portion surrounding said rotor and having arcuate delivery andsuction channels on opposite sides of said rotor arranged tosuccessively communicate with said cylinders as the rotor rotates andhaving open sides closed by the cylindrical surface of said rotor, saidbody portion having a pair of thrust balancing cbannels diametricallyopposite the delivery channel and communicating' therewith and locatedon opposite sides of said suction channel and having open sidesclosed-by the cylindrical surface of said rotor.

5. AA pump comprising a rotor formed in two sections spaced apartaxially and provided with V cylinders with their axes parallel to theaxis of rotationl of the rotor and with the cylinders of one section inalignment with the cylinders in the other section, a plurality ofpistons each having rigidly related piston portions at opposite endspositioned in the cylinders of the two Y sections of saidrotor, a bodyportion surroundlcate axially of said rotor as said rotor rotates whensaid anti-friction bearing occupies a position at an angle to saidneutralplane.

6. A pump comprising a rotor formed in two sections spaced apart axiallyand provided with cylinders with their axes parallel to the axis ofrotation of the rotor and with the cylinders of one section in alignmentwith the cylinders in the other section, a plurality of pistons eachhaving rigidly related piston portions at opposite ends positioned inthe cylinders of the two sections of said rotor, a body portionsurrounding the two sections of said rotor and having suction anddelivery channels successively communicating with said cylinders as saidrotor rotates, an anti-frictionibearing having inner and outer racessurrounding said pistons and located between the two sections of saidrotor, said pistons having spaced flanges intermediate the ends of saidpistons engaging the inner rac of said anti-friction bearing, and amember holding the outer race of said anti-friction bearing and pivotedabout an axis transverse to the axis of said rotor. i'1. A pumpcomprising a rotor formed in' two sections spaced apart axially andprovided with cylinders with their axes parallel to the axis of saidpistons engaging the inner race of said anti` means for rocking saidyoke in either direction with reference to a neutral plane.

8. A pump comprising a rotor formed in two sections spaced apart axiallyand provided with cylinders with their axes parallel to the axis ofrotation of the rotor and with the cylinders of one section inalignmentfwith the cylinders in the other section, a plurality ofpistons each having rigidly related piston portions at opposite endspositioned in the cylinders of thetwo-sections ofv said rotor, a bodyportion surrounding the two sections of said rotor and having suctionand delivery channels successively communicating with said cylindersassaid rotor rotates, an

anti-friction bearing having inner and outer races surrounding saidpistons and located between the two sections of said rotor, said pistonshaving spaced flanges intermediate the ends of friction bearing, a yokeholding the outer race of said anti-friction bearing and pivoted aboutan axis transverse to the axis of said rotor, means for rocking saidyoke to .either direction with reference to a neutral plane, and meansfor locking said yoke in its adjusted position.

9. A pump comprising a cylindrical rotor formed in two sections spacedapart and mechanically tied together and having a plurality f ofcylinders with the cylinders of one section rotation of the rotor andwith the cylinders of e one section in alignment with the cylinders inthe other section, a plurality of pistons each having rigidly relatedpiston portions at opposite ends positioned in the cylinders of the twosections of said rotor, a body portion surrounding the two sections ofsaid rotor and having suction and delivery channels successivelycommunicating with said cylinders as said rotor rotates, ananti-friction bearing having inner and` outer races surrounding saidpistons and located between the two sections of said rotor, said pistonshaving spaced ilanges intermediate the ends of said pistons engaging theinner race of said antifriction bearing, a yoke holding the outer raceof said anti-friction bearing and pivoted about an axis transverse tothe axis of said rotor,. and

aligning with the cylinders in the other section, a plurality of pistonseach having piston por- 4tions at opposite ends positioned in thecylinders said body lportion having at least one thrust balancingchannel diametrically opposite each delivery channel and communicatingwith the corresponding delivery channel and having open sides closed bythe cylindrical surface of said rotor, and means coacting with anintermediate portion of said pistons to cause saidpistons to reciprocateas said rotor rotates.

10. A pump comprising a' cylindrical rotor formed in two sections spacedapart and mechanically tied together and having a plurality of cylinderswith the cylinders of one section aligning with the cylinders in theother section, a plurality of pistons each having piston portions atopposite ends positioned in the cylinders of the two sections of saidrotor, a body portion surrounding the two sections of said rotor andhaving arcuate suction and delivery channels for each section of saidrotor on opposite sides of the corresponding sections of said rotor andarranged to successively communicate with the cylinders oi said rotorand having open sides closed by the cylindrical surface of said rotor,said body portion having a pair of thrust balancing channelsdiametrically opposite each delivery channel and communicating with thecorresponding delivery channel and located on opposite sides of thecorresponding suction channel and having open sides closed by thecylindrical surface of said rotor, and means coacting with anintermediate portion of said pistons to cause said pistons toreciprocate as said rotor rotates.

11. A pump comprising a cylindrical rotor having a plurality ofcylinders therein, pistons mounted within the cylinders, said pistonsand accents lsaid cylinders having their axes paralleling the axis ofrotation of the rotor, means for reciprocating the pistons as the rotorrotates, a. sleeve surrounding the rotor and having arcuate suc- Ktonfand delivery channels on opposite sides of -k the rotor arranged forsuccessive communication with the cylinders as the rotor rotates andhaving open sides closed by the cylindrical surface of the rotor, a bodyportion surounding said sleeve, said sleeve having at least one thrustbalancing channel diametrically opposite the delivery channel anddirectly communicating with the delivery channel and having an open sideclosed by the cylindrical surface of the rotor, whereby the pressureproduced in the delivery channel is transmitted directly to the thrustbalancing channel A diametrically opposite the delivery channel.

12. A pump comprising a rotor having a plurality of cylinders therein,pistons mounted within the cylinders, said pistons and said cylin- 20ders having their axes paralleling the axis of rotation of the rotor,means for reciprocating the pistons as the rotorrotates, a sleevesurrounding the rotor and having arcuate inner suction and deliverychannels on opposite sides of the rotor and having discharge andentrance channels on the outer side of said sleeve communicatingrespectively with said delivery and suction channels, and al bodyportion surrounding said sleeve and having inlet and outlet opena0I1,428,876

ingscommunicating with said entrance and discharge channelsrespectively, said sleeve and body portion having a pressed iit.

13. A pump comprising a cylindrical rotor having. a plurality ofcylinders therein, pistons 35 1,506,892

mounted within the cylinders, means for reciproeating the pistons as therotor rotates, a body portion cooperating with the rotor and havingdiametrically opposed arcuate suction and delivery channels arranged iorsuccessive commu- -nication with the cylinders as the rotor rotates andhaving open sides closed by the cylindrical surface of the rotor, saidbody portion having at least one thrust balancing channel diametricallyopposite the delivery channel and communieating with the deliverychannel and having an open side closed by the cylindrical surface oi therotor, whereby ,the pressure produced in the delivery channel istransmitted to' the thrust bal-V ancing channel diametrically oppositethe delivery channel.

ADAM ZISKA.

REFERENCES CITED The following references are of record in the file ofthis patent:

v UNITED STATES PATENTS Number Egersdorfer Sept. 2, 1924

